Device for rollably supporting a ball



May 12, 1964 KOHE] WAKAMATSU ETAL 3,132,904

DEVICE FOR ROLLABLY SUPPORTING A BALL Filed Nov. 13, 1962 5 Sheets-Sheet 1 May 12, 1964 KOHEl WAKAMATSU ETAL DEVICE FOR ROLLABLY SUPPORTING A BALL Filed Nov. 13, 1962 5 Sheets-Sheet 2 Fig. 7

M y 1964 KOHEI WAKAMATSU ETAL 3,132,904

DEVICE FOR ROLLABLY SUPPORTING A BALL Filed Nov. 13, 1962 5 Sheets-Sheet 3 Fig. 9

M y 1964 KOHEI WAKAMATSU ETAL 3,132,904

DEVICE FOR ROLLABLY SUPPORTING A BALL Filed Nov. 13, 1962 5 Sheets-Sheet 4 y 12, 1964 KOHEI WAKAMATSU ETAL 3,132,904

DEVICE FOR ROLLABLY SUPPORTING A BALL Filed Nov. 13, 1962 5 Sheets-Sheet 5 United States Patent DEVHCE FGR ROLLABLY SUPPGRTING A BALL Kohei Wakamatsu, Arnagasalri-shi, and liiitsuhiiro Goto,

Kure-shi, .iapan, assignors to Amagasairi iron 8: Steel Mfg. (30., Ltd Minami-iru, ()saka, .lapan, a corporation of Japan Filed Nov. 13, 1962, Ser. No. 236,889 4 Claims. (ill. 308-26) The present invention relates to devices for rollably supporting a ball and is intended to provide an improved device of the character described which is adapted to be fitted to a cradle, platform or like base member of mechanical equipment so as to enable it to be freely turned to any desired direction or to support such member in a manner so that it may be translated extremely lightly in any desired direction.

According to the present invention, there is provided a device for rollably supporting a ball which includes at least three spaced-apart thrust races cooperable to support the ball and each supported on the underside by an appropriate number of minor balls, said thrust races being arranged so as to supportingly contact the peripheral surface of the lower half of the ball at regular intervals, the points of contact of said thrust races with the ball being offset in the same direction by the same distance relative to the respective axes of rotation of said thrust races.

The present invention will now be fully described in connection with the accompanying drawings, in which:

FIGS. 1 to 8, inclusive, are schematic diagrams showing the principles of rolling movement of a ball upon which the present invention relies;

FIGS. 2 and 4 are side elevational views corresponding to FIGS. 1 and 3, respectively;

FIG. 9 is a vertical cross section of one embodiment of the invention;

FIG. 10 is a plan view of same;

FIG. 11 is a view similar to FIG. 9 illustrating another embodiment of the invention;

FIG. 12 is a plan view of the device shown in FIG. 11; and

FIG. 13 shows an apparatus for oscillating a ladle filled I with molten metal which employs the devices of the present invention.

Description will first be made with reference to FIGS. 1 to 8, which illustrate the principles of rolling movement of a ball upon which the present invention is based. In FIG. 1, if a force F is applied to the top point P (or permissibly to a side point) of the ball 1 in a direction as indicated by the arrow A, the ball 1 is advanced as indicated by the arrow A while rolling about the axis XX. Therefore, any point on the ball surface such as point B or C proceeds in a direction B or C which is parallel to .the direction A while describing a curve D or E (see FIG. 2).

When ball 1 rolls over the ground surface 2 in this manner, the friction occurring between the ball and the ground surface 2 is a rolling friction, therefore, a rolling movement may be imparted to the ball without applying any substantial force thereto.

On the other hand, if a barrier plate 3 is placed on such sliding friction is eliminated to impart a ball rolling rbnovement without necessitating any displacement of the all. such arrangement provided only on the underside of the ball 1. The supporting device includes a thrust race 5 supported on the underside by a number of minor balls 4 for rotation about an axis ZZ. The ball 1 is supported by the thrust race at a point ofiset from the axis of rotation ZZ by a distance h. It will be noted that if a force is applied to the ball 1 in a direction as indicated by the arrow A, a sliding friction occurs at the point of contact Q of the ball with the barrier plate 3 but at the point of contact R at the bottom of ball 1, a rotative force is imparted by the ball to the thrust race 5 to rotate the latter in a direction as indicated by the arrow S since the axis of rotation ZZ of the thrust race 5 is offset from the point of contact R. The ball thus effects rolling movement relative to the ball 1. It will be recognized that in this case the force required to rotate the ball 1 is reduced compared with the case friction occurs on both side and bottom surfaces of the ball as in FIG. 2.

FIG. 5 illustrates an arrangement similar to that shown in FIG. 3 except that it further includes a barrier plate 3 and a like supporting device attached thereto. In this arrangement, the ball is in rolling relation to each of the thrust races under the action of a force F applied in the direction of the arrow A, and no sliding friction occurs in any area. Therefore, the ball can rotate extremely lightly as long as its axis of rotation coincides with line X-X, that is, only when a rotative force is applied to the top point P of the ball 1 in the direction of the arrow A. If a force is applied which acts in the direction of the arrow A", the ball is caused to rotate about an axis X'X' allowing some sliding friction to occur against the side plate 3'.

To meet this situation, a further thrust race may be provided on the side plate 3 as shown in FIG. 6. In this case, any-force applied to the top point P in the direction of the arrow A" tends to rotate the ball 1 about an axis of rotation XX' while displacing the points of contact of the ball with the respective thrust race as indicated by the arrows H, I, and] on the ball surface. The thrust races each have an axis of rotation offset from the point of contact with the ball allowing it to rotate extremely lightly. In this arrangement, however, if a rotative force is applied in the direction of the arrow A', some sliding friction necessarily occurs as the axis of rotation Z of the bottom thrust race and its point of contact with the ball are aligned in a direction parallel to the line of force A". In addition, another point of contact Q is fixed and the adjacent thrust race remains stationary.

It is to be noted that these arrangements involve a like problem irrespective of the disposition of thrust races for supporting the ball.

FIGS. 7 and 8 illustrate the range in which such a problem may arise. In case of FIG. 7, that is, in case the point of contact a of the-ball 11 with a thrust race 16 lies on the line joining the center 0 of the ball and a surface point P at. which a force is applied to the ball, a sliding friction occurs when the line joining the axis of rotation ZZ of the thrust race and the point of contact on thereof with the ball coincides with the line of rotating movement of the ball as indicated by the arrow K or K. In this case, if the ball is rotated in a plane at right angles to the line Ooc as indicated by the arrow L or L, the point of contact a is fixed and the race remains stationary.

FIG. 8 illustrates another case which involves sliding friction. As with the case described above in connection with FIG. 7, if the ball rotates about an axis extending through the center 0 'of the ball and the point of contact on thereof with the thrust race,..the point of In FIG. 3, there is shown a supporting device of =3 contact a is stationary and the thrust race 16 remains still. Similarly, if the ball rotates in a plane parallel to the plane which includes the center of rotation Z of the race, point of contact a, and the center of the ball, a sliding friction occurs. Sliding friction is also involved when the plane in which the ball rotates is parallel to the line joining the center of rotation of the thrust race 16 and its point of contact at with the ball ill, as indicated by the arrow M or M. In this case, the drive force applied by the rotating ball to the thrust race 16 at the point of contact it apparently acts in the direction tangential to the ball as this contact is between a sphere and a plane and the tangent and the axis of rotation Z of the race are included in a single plane which is parallel to the plane in which the ball rotates. The drive force of the rotating ball, therefore, is resisted by the thrust race.

The device of the present invention has been designed taking the above points into consideration. FIGS. 9 to 12 illustrate several practical examples of utilizing the inventive device. The arrangement shown in FIG. 9 slightly differs from that of FIG. ll in the manner in which the ball is supported, as will be described below.

Referring first to FIGS. 9 and 10, the ball 11 is mounted in a housing 12 which is formed with a spherical recess 13 dimensioned more than enough to enclose the lower half of the ball ll. The recessed surface 13 is centered at O, which is the center of the ball as received in the recess, and is formed with three cylindrical bores 14, which are spaced apart from each other by a distance of 120 degrees and each inclined at an angle of 45 degrees relative to the center of curvature of the recessed surface E3 or the center of the ball 11. Furthermore, the cylindrical bores are each slightly offset from the point of contact of a thrust race (which will be described later) with the ball surface in a horizontal direction tangential to the spherical recessed surface 13. An appropriate number of minor balls 15 are arranged in each of said cylindrical bores 14 in contacting relation to the inner periphery thereof and a thrust race 16 is mounted on the minor balls 15. The ball 11 is supported by such three thrust races as illustrated. A plate 18 is secured to the top of the housing by screws 19 to hold the ball against dislodgement by way of an annular packing 17. In addition, the entire assembly is held against rotation by dowl es 2b. The housing 12 istplaced upon base 22 by way of spring means 21 as illustrated.

With the device of the above construction, the ball can effect rolling movement substantially in any plane as will readily be appreciated. Only, since the three cylindrical bores 14 are formed offset in a horizontal tangential direction as described above, some sliding movement is involved if the ball is rotated in a plane parallel to the plane including the points of contact at between the ball 11 and the three thrust races 16 in a direction as indicated by the arrow Aor in a direction opposite thereto though such rotation can never take place in practical applications of this device. Some consideration is required with this device to the situation dc scribed above with reference to FIG. 8, where the line u-Z joining the point of contact a and the center of thrust race M (which corresponds to line YY in FlG. 10) is parallel to a vertical plane in which the ball 1 rotates. In this case, however, the other two of the three ball supporting races l6 are rotated by forces applied by way of the ball 11 and these forces include rotative components acting in different direc tions because of the inclination of the race surfaces upon which the forces act and thus cause the remaining thrust race, which may otherwise involve some sliding friction, to rotate about its own axis of rotation. The difiiculty in the situation as illustrated in FIG. 8 is thus overcome with the device shown in FIGS. 9 and 10. Moreover, this mechanism of eliminating sliding friction is compensated for by the arrangement of the springs 21 for supporting the ball housing 12 on the base 22 in which the resiliency of springs 21 assists in elirninata ing any directionality of the ball 11. It is to be noted, however, that the primary purpose of the springs 21 is to make uniform the loading upon such device in cases where a number of similar units are arranged in a row for carrying an object. In such cases, it will be appreciated that the springs may yield as required to allow the balls of the respective units to bear the object at a level such that the balls are uniformly loaded.

As apparent from the foregoing, the device according to the present invention provides for rolling rotation in all direction other than in the direction of the arrow A and that opposite thereto, and not involving any undue drag due to sliding friction, is rotatable extremely lightly. It will be recognized, therefore, that the device is very advantageous for use with a carriage, a traversing platform or other like member. Where such member is supported by the inventive device or is attached therewith, it can be traversed under a very limited drive power without making the supporting assembly unduly bulky or complicated. In addition, the device with its ball and thrust races can withstand an extended period of service becauseof minimized wear of the component parts. These advantages of the inventive device are extremely valuable from both technical and economical standpoints as will readily be appreciated by those skilled in the art.

Additionally, it is noted that the minor balls for supporting each of the thrust races, the thrust races and the main ball'can be readily removed and replaced by removing the plate 18 for example in case any of these components be damaged by some reason or other.

The supporting device shown in FIGS. 11 and 12 is an improvement over the device described hereinbefore and shown in FIGS. 9 and 10. The point of improvement is to enable rolling rotation in the direction of the arrowA and that opposite thereto which is impossible with the supporting device shown in FIGS. 9 and 10, though such is substantially out of question in practical applications. The device of FIGS. 11 and 12 is generally similar to the device shown in FIGS. 9 and 10 except that the plane including the points of contact on between the ball 11 and the respective thrust races 16, which coincides inFIG. 10, with the plane including the center of the top surfaces of the respective races, is raised in the device shown in FIGS. 11 and 12 by a distance it so that the plane including the contact points ,8 lies apart from the plane including the centers of the respective race surfaces. Such arrangement of contact points 5 in effect corresponds to twisting the thrust races within certain limits. The contacting relationship between the'ball 11 and the thrust races twisted is such that the lines joining the centers 7 of the race surfaces with the respective contact points ,8 extend in respective angular directions which differ from each other with respect to the rotation of the ball, and

thus is effective to alleviate the limitation inherent to the arrangement shown in FIGS. 9 and 10.

A practical application of the device of the present invention is illustrated in FIG. 13. The apparatus shown is an apparatus for oscillating a ladle 104 filled with molten metal. Specifically, the apparatus is arranged to impart to the ladle 104 an eccentric horizontal rotary movement without rotating it about its own axis for mixing the molten metal in the ladle for refining purposes. The ladle 1M is generally frustoconical and fixedly mounted on a movable frame 105, which in turn is mounted on a fixed base 102 by devices 103 of the present invention for limited horizontal movement.

A crank shaft 106 is rotatably mounted vertically in the fixed base Th2 and has a crank portion 107 in engagement with the movable frame so that as the crank shaft 1% is rotated by way of a suitable drive mechanism the movable frame effects an eccentric rotary movement in its own plane, as will readily be observed. The movable frame 105 is resiliently connected to the fixed frame below by way of a plurality of springs 111 so that it may effect limited horizontal movement relative to the stationary frame but is held against any continuous rotating movement. The devices 103, being constructed as described hereinbefore, can bear quite a heavy load and involve only limited frictional drags, and thus are highly desirable with such apparatus as shown in FIG. 13.

What is claimed is:

1. A device for rollably supporting a ball comprising a housing, a ball disposed in said housing to be supported therein, and at least three thrust bearings adapted to engage the lower half surface of said ball to support the ball above the inner wall of said housing, said thrust bearings each including an upper race in contact with said ball, a lower race fixed to the inner wall of said housing and a plurality of minor balls interposed between said upper and lower races, the points of contact of said ball with the upper races being offset from the respective axes of said thrust bearings in the same angular direction with respect to the respective axes of said thrust bearings.

2. A device as claimed in claim 1 in which said thrust bearings are arranged in a horizontal plane at regular intervals and the amount of ofiset of said point of contact is uniform for all of the thrust bearings.

3. A device as claimed in claim 2 in which the lower race of each of said thrust bearings includes the bottom and side walls of a bore formed in the inner wall of said housing.

4. A device as claimed in claim 2 further comprising a base arranged beneath the ball housing thereby eliminating any directionality of the ball, and spring means disposed between said base and housing to resiliently support the housing.

References Cited in the file of this patent UNITED STATES PATENTS 717,124 Sage Dec. 30, '1902 2,225,753 Milich Dec. 24, 1940 2,490,879 Milich Dec. 13, 1949 2,623,795 Birch Dec. 30, 1952 2,650,865 Townsend Sept. 1, 1953 2,740,154 Osner Apr. 3, 1956 2,818,737 Barrett Jan. 7, 1958 FOREIGN PATENTS 376,740 Great Britain July 13, 1932 

1. A DEVICE FOR ROLLABLY SUPPORTING A BALL COMPRISING A HOUSING, A BALL DISPOSED IN SAID HOUSING TO BE SUPPORTED THEREIN, AND AT LEAST THREE THRUST BEARINGS ADAPTED TO ENGAGE THE LOWER HALF SURFACE OF SAID BALL TO SUPPORT THE BALL ABOVE THE INNER WALL OF SAID HOUSING, SAID THRUST BEARINGS EACH INCLUDING AN UPPER RACE IN CONTACT WITH SAID BALL, A LOWER RACE FIXED TO THE INNER WALL OF SAID HOUSING AND A PLURALITY OF MINOR BALLS INTERPOSED BETWEEN SAID UPPER AND LOWER RACES, THE POINTS OF CONTACT OF SAID BALL WITH THE UPPER RACES BEING OFFSET FROM THE RESPECTIVE AXES OF SAID THRUST BEARINGS IN THE SAME ANGULAR DIRECTION WITH RESPECT TO THE RESPECTIVE AXES OF SAID THRUST BEARINGS. 